Catalyst and catalyst supports, with inorganic nitrates, for olefin dimerization

ABSTRACT

This invention concerns catalyst systems for olefin dimerization wherein said catalyst system comprises at least one elemental alkali metal catalyst, supported on an alkali metal carbonate support, wherein said support includes an inorganic nitrate. This invention further concerns processes for the dimerization of olefins. The catalytic support can optionally comprise a carbonaceous compound(s), an inorganic oxide(s), or a mixture thereof. Furthermore, the catalyst system optionally can comprise at least one promoter selected from the group consisting of elemental copper, elemental cobalt, finely divided stainless steel, finely divided glass, or mixtures thereof.

This application is a division of application U.S. Ser. No. 07/375,563,filed July 5, 1989 now U.S. Pat. No. 4,950,632.

BACKGROUND OF THE INVENTION

This invention relates to alkali metal carbonate supported elementalalkali metal catalysts. It is known in the art to prepare an alkalimetal carbonate catalyst support by making a thick paste and eventuallyforming a pelletized, tabletted, and/or granular support. It is alsoknown in the art to use an alkali metal carbonate to support anelemental alkali metal to form a catalyst system useful to promoteolefin dimerization. However, these types of catalysts and catalystsupports can suffer from low selectivity for the desired reactionproduct(s). Thus, it can be difficult to process and obtain economicallyuseful amounts of the reaction product(s) that are desired.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a simplified process toprepare an improved alkali metal carbonate catalyst support.

It is a further object of this invention to provide a method to preparean improved alkali metal carbonate supported elemental alkali metalcatalyst system.

It is yet another object of this invention to provide an improvedcatalyst system for the dimerization of olefins.

Accordingly, the present invention provides an alkali metal carbonatecatalyst support which is prepared from a thick paste comprising analkali metal carbonate, water, and an inorganic nitrate. The resultantthick paste is formed into a particulate product and calcined to give animproved catalyst support.

In another embodiment of the invention, an elemental alkali metal issupported on the inventive alkali metal carbonate support to form animproved catalyst system for olefin dimerization. The novel catalystsystem, when used to dimerize olefins, provides improved selectivity tothe desired reaction product(s).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a process to prepare a catalyst supportwhich comprises the steps of forming a thick paste comprising an alkalimetal carbonate, water, and an inorganic nitrate; forming a particulateproduct from said pate; and calcining said particulate product. Theparticulate product can be formed by grinding and sieving prior tocalcining or it can be formed into an extrudate, pellets, tablets,pills, or any other granular form prior to calcining.

In accordance with one embodiment of the invention, the thick pastecomprising an alkali metal carbonate, water, and an inorganic nitratecan further comprise a carbonaceous compound.

In accordance with a further embodiment of the invention, the thickpaste comprising an alkali metal carbonate, water, and an inorganicnitrate can further comprise a non-acidic inorganic oxide.

In accordance with yet another embodiment of the invention, thepreviously prepared particulate alkali metal carbonate catalyst supportcan be contacted with at least one elemental alkali metal to produce acatalyst composition.

In accordance with yet a further embodiment of the invention, the alkalimetal carbonate catalyst support and the elemental alkali metal catalystcomposition can be contacted with at least one promoter.

SUPPORTS

Commercially available alkali metal carbonate in the form of powder,granules, or the like, is mixed with an inorganic nitrate and sufficientwater to form a thick paste. This thick paste usually comprises fromabout 1 to about 50 weight percent of inorganic nitrate, based upon thetotal weight of the alkali metal carbonate, and sufficient water todissolve the inorganic nitrate, and yet not dissolve the alkali metalcarbonate. The amount of water sufficient to form a thick paste, whereinthe inorganic nitrate is dissolved and the alkali metal carbonate is notdissolved, is based on the solubility of the inorganic nitrate in, andthe temperature of, the water. Preferably, the thick paste comprisesfrom about 3 to about 40 weight percent of inorganic nitrate, and mostpreferably, the thick paste comprises from about 5 to about 30 weightpercent of inorganic nitrate, based upon the total weight of the alkalimetal carbonate. Described in another way, the inorganic nitrate can befrom about 1 to about 33 weight percent based on the calcined catalystsupport. Preferably, the inorganic nitrate can be from about 3 to about30 weight percent, and most preferably, the inorganic nitrate can befrom about 5 to about 23 weight percent, based upon the calcinedcatalyst support. Too much inorganic nitrate can result in a catalystwith low strength and inferior performance (low conversion andselectivity). Too little inorganic nitrate gives no improvement overpotassium carbonate by itself. If too much water is used to form thethick paste and the alkali metal carbonate dissolves, then theprocessability of the catalyst becomes more difficult (due to the excesswater that must be removed). If too little water is used, the inorganicnitrate will not dissolve and can cause nonhomogeneous catalyst mixturewith resulting poor catalyst performance. Furthermore, if too little ortoo much water is used, formation of a particulate product can bedifficult.

Any alkali metal carbonate can be used in the preparation of thecatalyst support. Preferably, sodium carbonate or potassium carbonate isused, for ease of use and common availability.

Any inorganic nitrate can be used in the preparation of the catalystsupport. Suitable inorganic nitrates include, but are not limited to,cadmium nitrate, cesium nitrate, lead nitrate, lithium nitrate,potassium nitrate, rubidium nitrate, silver nitrate, sodium nitrate, andmixtures thereof. Preferably, sodium nitrate and potassium nitrate areused and most preferably, potassium nitrate is used, for ease of use,common availability, and compatibility with the alkali metal carbonate.

The thick paste can then be formed into a particulate product prior tocalcining. The paste can be formed into an extrudate using an extruder.The extrudate can be any diameter, but for best catalytic activity andand ease of handling and processability, the extrudate is from about1/16 to about 1/4 inch in diameter. After the extrudate passes throughthe die, the extrudate can be cut into uniform lengths, if desired.However, uniform lengths are not always necessary, so the extrudate canbe allowed to break on its own, into any length. If the extrudate isallowed to break on its own, it will usually have a length of about 2 toabout 7 times the diameter width. Usually, the extrudate is allowed tobreak of its own accord because of ease of manufacture.

The thick paste after drying and granulation can also be formed intotablets using a die press, a punch press, or a pelleting machine.Tablets are usually very uniform in size. Tablets look similar to anextrudate, except the two ends of each cylindrical tablet are convex,not blunt.

The thick paste can also be formed into pellets and/or pills. Pelletsand pills can be defined as any other type of form that are not preparedusing an extruder, a die press, punch press, or pelleting machine. Oneexample of an apparatus used to make pellets or pills is a diskspherudizer. A disk spherudizer, or disk pelletizer, is a flat, circulardisk with a lip perpendicularly attached around the circumference of thedisk. The disk is mounted at an angle and rotates; scrapers arestationarily mounted above the disk. The disk rotating speed, angle ofthe disk, solids feed rate onto the disk, and ratio of liquids to solidsall control the diameter of the pellets. Usually, the solids and liquidsare not mixed prior to introduction onto the disk, but they can bepre-mixed.

Another method of forming a particulate product from the thick paste isto oven dry the thick paste under conditions of time and temperaturesufficient to insure that substantially all of the water has been drivenoff. The dried paste can then be broken into pieces and fractionated bysuitable means such as, for example, by passing through the appropriatemesh size screen seives to recover a desired particle size fraction.

The alkali metal carbonate/inorganic nitrate support can optionallycontain at least one carbonaceous compound. The carbonaceous compoundcan be added simultaneously with the alkali metal carbonate, inorganicnitrate, and water. For purposes of this disclosure, the term"carbonaceous compound" is intended to include various forms of theelement carbon, including, but not limited to carbon black, charcoal,coconut charcoal, amorphous graphite, crystallite graphite, and thelike, as well as mixtures of any tow or more thereof. Finely dividedgraphite is presently preferred because it is useful both as a dielubricant for the pelleting process and it imparts improved activity tothe finished dimerization catalyst. The carbonaceous compound, ifemployed, comprises from about 1.0 to about 10 weight percent of thetotal alkali metal carbonate. Preferably, the carbonaceous compoundcomprises from about 0.5 to about 4 weight percent, and most preferably,the carbonaceous compound comprises from about 0.8 to about 2 weightpercent of the support. Too much of the carbonaceous compound can causea lower strength support. Too little of the carbonaceous compound canhave a detrimental effect on catalyst activity.

The alkali metal carbonate/inorganic nitrate support can also optionallycontain at least one non-acidic inorganic oxide. The non-acidicinorganic oxide can be added simultaneously with the alkali metalcarbonate, inorganic nitrate, and water. The non-acidic inorganic oxide,if employed, comprises from about 1 to about 10 weight percent of thealkali metal carbonate. Suitable non-acidic inorganic oxides include,but are not limited to, alumina, such as alpha-alumina, silica, and/orsilica-alumina; magnesia-titania; thoria; magnesium; titania; zirconia;and mixtures thereof.

Once the catalyst support is formed and dried, it should be calcined inan oxygen containing atmosphere at a temperature in the range of about80° to about 400° C., preferably about 350° C. In any case, it ispreferable that the temperature be less than the decompositiontemperature of the inorganic nitrate. If the calcining temperature isabove the decomposition temperature of the inorganic nitrate then theinorganic nitrate decomposes to the oxide and the catalyst is notimproved. The catalyst support should be calcined for about 5 minutes toabout 10 hours, preferably about 3 hours in order to insure completecalcination and through dryness. The catalyst support is then storedunder a dry, oxygen-free atmosphere until needed for further treatment.

As used in this disclosure, the terms "alkali metal carbonate/inorganicnitrate support" and "catalyst support" are interchangeable and refer toany of the inventive supports described above. Furthermore, even throughthe catalyst support is labelled a support, it is possible that theinventive supports may provide or enhance some catalytic activity.

CATALYSTS AND PROMOTERS

Catalysts systems employed in the practice of this invention compriseone of the alkali metal carbonate/inorganic nitrate supports describedabove, at least one elemental alkali metal catalyst, and optionally oneor more of the following additional promoters:

elemental copper,

elemental cobalt,

finely divided stainless steel,

finely divided glass, and

mixtures of two or more thereof.

It should be recognized, however, that the catalyst systems of theinvention can contain additional components which do not adverselyaffect the catalyst performance, such as, for example, pigments, dyes,processing aids, inert fillers, binders and the like.

The alkali metals contemplated to be within the scope of the inventioninclude lithium, sodium, potassium, rubidium and cesium. While theproportion of alkali metal combined with the alkali metalcarbonate/inorganic nitrate support can vary appreciably, generally atleast about one weight percent of alkali metal based on the total weightof treated support will be employed. Generally, about 1 to about 20weight percent alkali metal will be employed, with about 2 to about 15weight percent preferred. An alkali metal loading of about 3 to about 10weight percent based on the total weight of treated support is mostpreferred for most efficient use of reagents, high catalyst activity andselectivity, and ease of catalyst preparation. Potassium is thepreferred elemental alkali metal due to its ready availability as wellas relative ease and safety in handling.

The proportion of optional promoter on the alkali metal carbonatesupport can vary appreciably, but generally, at least one weight percentof the optional promoter based on the total weight of treated supportwill be employed. The following amounts are provided for additionalguidance:

    ______________________________________                                        Loading, Weight Percent                                                       Promoter Broad       Intermediate                                                                             Preferred                                     ______________________________________                                        Cu       1-30        3-20       5-12                                          Co       1-50        3-25       5-15                                          *SS      1-80        3-60       5-50                                          Glass    1-50        2-25       3-15                                          ______________________________________                                         *SS = Stainless Steel                                                    

The general procedure for preparation of a catalyst system, aftercalcining the support, involves heating the alkali metalcarbonate/inorganic nitrate support to a temperature in the range ofabout 80° to about 350° C. Preferably a temperature slightly above themelting point of the particular alkali metal employed, and below thedecomposition temperature of the inorganic nitrate is used. Afterheating the particulate support, the particulate support is contactedwith at least one elemental alkali metal in a dry, oxygen-freeatmosphere, such as, for example, N₂, Ar, or the like, at a temperaturesufficient to cause the alkali metal to melt, and yet below thedecomposition temperature of the inorganic nitrate. The contacting,which is done in an oxygen-free atmosphere, is preferably carried outwith suitable mixing to ensure even distribution. Suitable temperaturesfor the contacting step will vary with the particular alkali metalemployed. For example, with elemental potassium, temperature sin therange of about 80° to about 100° C. are preferred, while with elementalsodium, temperatures in the range of about 100° to about 140° C. arepreferred.

Wile the alkali metal treated support is maintained at or above themelting point of the particular alkali metal used, any desiredpromoter(s), such as, for example, finely divided stainless steel orelemental copper, can be gradually added while the treated catalyst iscontinuously stirred. The catalyst system is then ready to be charged tothe reactor.

Optionally, the alkali metal carbonate/inorganic nitrate support, onceelemental alkali metal and any desired promoters have been depositedthereon, can be subjected to a subsequent heating step, in anoxygen-free atmosphere, to ensure as uniform a distribution as possibleof the various promoters on the surface of the alkali metalcarbonate/inorganic nitrate support. Thus, the finished catalyst can besubjected to a temperature in the range of at least about 80° C. for atime in the range of about 0.1 to 4 hours. A temperature in the range ofabout 150° to about 250° C. for a time in the range of about 0.5 toabout 2 hours is presently preferred for the most uniform distribution.

Optionally, prior to charging the reactor, the catalyst system can bemixed with an inert substance to dilute the catalyst system and decreasethe rate of olefin dimerization. Any inert substance which has nocatalytic activity in an olefin dimerization reaction can be used. Oneexample of such an inert substance is glass beads.

As indicated by the variety of supports, alkali metal components, andpromoters included within the scope of the invention, numerous catalystcombinations are possible. Any combination of the alkali metal andoptional promoters disclosed can be supported on any alkali metalcarbonate/inorganic nitrate support disclosed. Some possiblecombinations are described in detail in the examples which follow. Thecombination of support, alkali metal and promoter(s) which one maychoose to employ will depend on a variety of variables such as, forexample, reactor configuration, reaction temperature and pressure,olefin feed employed, rate of olefin feed, and conversions desired.

REACTANTS

Reactants applicable for use in the process of the invention are olefincompounds which can (a) self-react, i.e., dimerize, to give usefulproducts such as, for example, the self-reaction of propylene gives4-methyl-1-pentene; and/or (b) olefinic compounds which can react withother olefinic compounds, i.e., co-dimerize, to give useful productssuch as, for example, co-dimerization of ethylene plus propylene gives1-pentene, co-dimerization of ethylene and 1-butene gives3-methyl-1-pentene and so forth. As used herein, the term "dimerization"is intended to include both self-reaction and "co-dimerization" asdefined above.

Suitable dimerizable olefinic compounds are those compounds having fromabout 3 to about 30 carbon atoms and having at least one olefinic doublebond and at least one allylic hydrogen atom, i.e., at least one hydrogenatom attached to a carbon atom adjacent to a double-bonded carbon atom.Exemplary compounds include, but are not limited to, acyclic and cyclicolefins such as for example propylene, 1-butene, 2-butene, isobutylene,1-pentene, 2-pentene, 1-hexene, 2-hexene, 1-heptene, 2-heptene, the fournormal octenes, the four normal nonenes and so forth; 3-methyl-1-butene,2-methyl-2-butene, 3-methyl-1-pentene, 3-methyl-2-pentene,4-methyl-1-pentene, 4-methyl-2-pentene, tetramethylethylene and thelike; cyclopentene, cyclohexene, methylcyclopentene, methylcyclohexene,and the like and mixtures of any two or more thereof.

Suitable co-dimerizable olefinic compounds are those compounds havingfrom about 2 to about 30 carbon atoms, including all the compoundscontemplated within the scope of "dimerizable" olefinic compounds asindicated above. In addition, olefinic compounds which do not have atleast one allylic hydrogen atom are also included within the scope ofco-dimerizable olefins. Exemplary compounds in addition to thoseindicated above, include, but are not limited to ethylene,3,3-dimethyl-1-butene, ditertiarybutyl ethylene and the like andmixtures of any two or more thereof.

The compounds indicated above as dimerizable olefinic compounds arecapable of undergoing both self-reaction, i.e., dimerization, andcross-reaction, i.e., co-dimerization, with other members of the samegroup or with those compounds designated as co-dimerizable. Theco-dimerizable compounds which do not have at least one allylic hydrogenmay be capable of isomerization to form an olefin having an allylichydrogen under the reaction conditions employed. If such isomerizationis not possible, then those non-isomerizable, co-dimerizable compoundswhich do not have at last one allylic hydrogen must be contacted with atleast one of the "dimerizable" compounds in order to facilitate thedesired co-dimerization reaction. In other words, the co-dimerizablecompounds which do not have at least one allylic hydrogen atom and arenot capable of isomerization to produce an olefin having at least oneallylic hydrogen are therefore not capable of reacting with themselvesunder the reaction conditions employed for the dimerization reaction.

REACTION CONDITIONS

The dimerization reaction of the invention can be carried out usingeither batch or continuous types of operation, although the catalysts ofthe invention are particularly well suited for continuous, fixed bed,operation. Suitable equipment such as for example autoclaves, tubularreactors and the like as are well known in the art can be employed. Nospecial materials of construction are required so that steel, stainlesssteel, glass-lined reactors, or the like can be employed.

The reaction temperature can vary depending on the catalyst and feed(s)employed. Typically, a temperature range of about 50° to about 250° C.is suitable. Temperatures of about 80° to about 200° C. are preferredwith a range of about 120° to about 170° C. most preferred becauseoptimum reaction rates are obtained with minimum by-product formation.

The dimerization reaction can be carried out by contacting thedimerizable olefins with catalyst in the liquid phase or the gas phase,depending on the structure and molecular weight of the olefin, as wellas reaction temperature and pressure employed. Pressure during thedimerization reaction can vary between wide limits. In general, higherpressures favor the progress of the reaction. Thus, pressures ofatmospheric up to about 10,000 psig and higher are suitable. Preferably,pressures of about 100 to about 5,000 psig are employed, with pressureof about 1,000 to about 4,000 psig most preferred in order to achieve agood balance between reaction rate and minimize equipment and operatingcosts necessitated by very high reaction pressures.

If the reaction is carried out in the liquid phase, solvents or diluentsfor the reactants can be used. Saturated aliphatic hydrocarbons, e.g.,pentane, hexane, cyclohexane, dodecane; aromatic compounds, preferablythose without an alpha-hydrogen (which would be capable of undergoingalkylation under the reaction conditions) such as benzene andchlorobenzene are suitable. If the reaction is carried out in thegaseous phase, diluents such as aliphatic hydrocarbons, for examplemethane, ethane and/or substantially inert gases, e.g., nitrogen, argon,can be present.

The contact time required for the dimerization reaction depends uponseveral factors such as for example the activity of the catalyst,temperature, pressure, structure of the reactants employed, level ofconversion desired, and the like. The length of time during which thedimerizable olefinic compounds are contacted with catalyst can varyconveniently between about 0.1 seconds and about 24 hours althoughshorter and longer contact times can be employed. Preferably, times ofabout one minute to about 5 hours are employed. Where reaction iscarried out in continuous fashion, it is convenient to express thereactant/catalyst contact time in terms of weight hourly space velocity(WHSV), i.e., the ratio of the weight of reactant which comes in contactwith a given weight of catalyst per unit time. Thus, a WHSV of about 0.1to about 10 will be employed. A WHSV of about 0.5 to about 5 ispreferred, with about 1 to about 4 WHSV most preferred for optimumcatalyst productivity.

PRODUCTS

The olefinic products of the invention have established utility in awide variety of applications such as for example as monomers for use inthe preparation of homopolymers, copolymers, terpolymers, e.g., as thethird component of ethylene-propylene terpolymers useful as syntheticelastomers, and the like.

A further understanding of the present invention and its advantages willbe provided by reference to the following examples.

EXAMPLES

In each of the following Examples, typically, the dimerization ofpropylene was carried out in a steam heated 316 stainless steel tubularreactor (1/2"×20"). The catalyst system, bounded above and below bysmall volumes of glass beads, was combined with 25 grams of an inertsubstance, i.e., no dimerization catalytic activity, to dilute thecatalyst system and thus reduce and control the reaction rate. Thecontents of the tubular reactor were heated to the reaction temperatureof about 160° C. at about 1500 psig and propylene was pumped into thereactor at a rate of about 120 mL/hr. After about 1.5 hours of reactiontime and each one hour thereafter for the following 6 hours, a samplewas collected and analyzed by gas liquid chromatography (glc). Thesummarized results represent the analysis of the last dimerizationsample collected.

EXAMPLE

The granular catalyst supports were prepared from commerciallyavailable, anhydrous potassium carbonate (ACS reagent grade), graphite(ACS reagent grade), and deionized water. The potassium carbonate andgraphite (1 weight percent of potassium carbonate) were then mixedtogether with either potassium acetate (ACS reactant grade) or potassiumnitrate (ACS reagent grade), as the tested components. This resultingmixture was made into a thick paste by the addition of water. Usuallyabout 2 milliliters of water were added to about 1 gram of the mixturein order to form the paste. The thick paste was thoroughly mixed andthen dried. The dried paste was then ground to about 6 mesh and calcinedto about 350° C. for about 3 hours in an oxygen containing atmosphere.

The resulting support was allowed to cool, in an oxygen-free atmosphere,to about 85° C., at which time about 5 weight percent of elementalpotassium, based on the calcined catalyst support weight, was added. Thecatalyst system was then heated to 200° C. for 1 hour and then stored ina dry, inert atmosphere until used.

The catalysts and the results of the corresponding propylenedimerization reactions are summarized in Table One. As used in theseExamples, 4-methyl-1-pentene is designated as 4MP1 and4-methyl-2-pentene is designated as 4MP2.

                  TABLE ONE                                                       ______________________________________                                              Additional                                                                    Support     Propylene   Product 4MP1                                    Run   Component   Conv. %     to 4MP1%                                                                              4MP2                                    ______________________________________                                        1     None        13.8        88.7    24.7                                    2     10% K.sub.2 C.sub.2 H.sub.3 O.sub.2                                                       12.8        88.4    23.2                                    3     20% KNO.sub.3                                                                             11.8        90.1    37.3                                    4     10% KNO.sub.3                                                                             12.8        90.0    38.5                                    ______________________________________                                    

After the propylene dimerization, the catalyst systems from Runs 1, 3,and 4 were removed from the dimerization reactor and examined. Eachcatalyst system showed some fines, however, the control catalyst, Run 1,had an apparent breakdown of the catalyst system, as indicated by theconsiderable amount of structural degradation of the catalyst system.The other two Runs that were examined did not have any such breakdown ofthe catalyst system.

Comparison of the percent selectivity to 4MP1, and the 4MP1/4MP2 productratio indicate that catalyst systems made with an inorganic nitrateproduce better results than catalyst systems made within an inorganicnitrate. Consequently, the addition of an inorganic nitrate, to acatalyst support, for a catalyst system, for olefin dimerization, showsan improvement over similar catalyst systems prepared without aninorganic nitrate in the catalyst support.

The Examples have been provided merely to illustrate the practice of theinvention and should not be read so as to limit the scope of theinvention or the appended claims in any way. Reasonable variations andmodifications, not departing from the essence and spirit of theinvention, are contemplated to be within the scope of patent protectiondesired and sought.

That which is claimed is:
 1. A dimerization process comprisingcontacting at least one olefin under dimerization conditions with acatalyst comprising:a) an elemental alkali metal; and b) a supportformed by preparing a thick paste comprising an alkali metal carbonate;from about 1 to about 50 weight percent inorganic nitrate, based on theweight of the alkali metal carbonate; and water, at a temperature and inan amount sufficient to dissolve the inorganic nitrate, but insufficientto dissolve the alkali metal carbonate; forming a particulate productfrom said paste; and calcining said particulate product at a temperatureless than the decomposition temperature than said inorganic nitrate;wherein said elemental alkali metal is supported on said support.
 2. Aprocess according to claim 1 wherein said elemental alkali metal isselected from the group consisting of sodium, potassium, and mixturesthereof.
 3. A process according to claim 1 wherein said elemental alkalimetal is from about 1 to about 20 weight percent of said supportcarbonate.
 4. A process according to claim 1 wherein said alkali metalcarbonate is selected from the group consisting of sodium carbonate,potassium carbonate, and mixtures thereof.
 5. A process according toclaim 1 wherein said inorganic nitrate is selected form the groupconsisting of cadmium nitrate, cesium nitrate, lead nitrate, lithiumnitrate, potassium nitrate, rubidium nitrate, silver nitrate, sodiumnitrate, and mixtures thereof.
 6. A process in accordance with claim 1wherein said thick paste further comprises a carbonaceous material;which is from about 0.1 to about 10 weight percent of the alkali metalcarbonate, and is selected from the group consisting of carbon black,charcoal, coconut charcoal, amorphous graphite, crystallite graphite,and mixtures thereof.
 7. A process according to claim 1 wherein saidthick paste further comprises a non-acidic inorganic oxide which is fromabout 1 to about 10 weight percent of said alkali metal carbonate, andis selected from the group consisting of alpha-alumina, silica,silica-alumina, magnesia-titania, thoria, magnesia, titania, zirconia,and mixtures thereof.
 8. A process according to claim 1 wherein saidparticulate product is formed by drying the said thick paste underconditions suitable to remove essentially all the water from said pasteand then grinding the thus-dried paste to form said particulate product.9. A process according to claim 1 wherein said particulate product iscalcined in an oxygen containing atmosphere at a temperature below thedecomposition temperature of said inorganic nitrate for a time withinthe range of from about 5 minutes to about 10 hours.
 10. A processaccording to claim 1 further comprising contacting said catalyst with atleast one promoter selected from the group consisting of finely dividedstainless steel, elemental copper, elemental cobalt, finely dividedglass, and mixtures thereof.
 11. A process according to claim 1 whereinsaid contacting is carried out at a temperature in the range of fromabout 50° C. to about 250° C., and a pressure in the range of aboutatmospheric to about 10,000 psig.
 12. A process according to claim 1wherein said olefin is propylene.
 13. A process for the production of4-methyl-1-pentene comprising contacting propylene under dimerizationconditions with a catalyst comprising:a) elemental potassium; and b) asupport formed by preparing a thick paste containing an alkali metalcarbonate; from about 1 to about 50 weight percent inorganic nitrate,based on the weight of the alkali metal carbonate; and water, at atemperature and in an amount sufficient to dissolve the inorganicnitrate, but insufficient to dissolve the alkali metal carbonate;forming a particulate product from said pate; and calcining saidparticulate product at a temperature less than the decompositiontemperature than said inorganic nitrate; wherein said elementalpotassium is supported on said support.
 14. A process according to claim13 wherein said particulate product is calcined in an oxygen containingatmosphere at a temperature within the range of from about 250° C. toabout 400° C. for about 5 minutes to about 5 hours.
 15. A processaccording to claim 13 wherein said contacting is carried out in atemperature in the range of from about 80° C. to about 200° C., and apressure in the range of from about 1000 psig to about 4000 psig.
 16. Aprocess according to claim 1 wherein said olefin is an olefinic compoundhaving from about 2 to about 30 carbon atoms per molecule.
 17. A processaccording to claim 16 wherein said olefin is propylene and is dimerizedto 4-methyl-1-pentene.